Windgrams and Local Lapse rate C°/1000' NWS Forecast synopsis below.
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ASP etc.Windgram Reading Explained
- Wind-Barbs are in knots. 1 full barb = 10knots. If a single barb is colored green it is between 7 and 9 knots.
- Numbers at the top are the W* or the expected Thermal updraft velocity in meters/second without cloudsuck or ridgelift at that time.
- Small clouds represent the expected LCL (lowest cloudbase), but do not mean that there will be clouds.. LCL is listed on the Blipspots
- Areas of white cross-hatching are times and levels where relative humidity > the "rhcut" number in the lower right, usually 94% so actual clouds are very likely there. I'm trying different cutoffs to get Marine stratus to show up better. Does it work at your site?
- "Paragliders" hover at the maximum expected altitude for soaring given a 1.1m/s or 221fpm sink rate.
- The colors in the background represent the "local" lapse rate at each time and altitude. Red is unstable and if it continues up off the chart it will likely mean big showers and or thunderstorms. When the unstable region only goes a bit above launch, that means strong "bullet" thermals in that region.
Where the background color shows, any lift will be either lucky or induced by winds hitting the terrain.
See this link for a summary of the different ways we try to measure instability.
- The Reported Latitude and Longitude has been chosen for the best match on the RASP model topographic data to the altitude and aspect of the site. (If you understand this and think a different grid square would better represent some site, let me know. They are not meant to be the same as your gps reads when on launch.)
- The altitude scale represents constant altitude connected with white reference lines.
The pressure heights vary during the day and are represended by the near horizontal red lines.
If the red line has a significant slope it indicates that the atmospheric pressure is changing dramatically over the course of the day.
For reference, pressure and altitude correspond at between 26ft and 32ft /1 Hpa(mb). depending mainly on temperature and pressure, but a little bit on moisture content. This means every 10mb accounts for between 260 and 320ft and that the 850mb level is usually around 5000feet while Sea Level is 1014 ish, on average. The correspondence can easily change by 300feet over the course of a day, so think of these as relative altitudes, not absolute.
Given today's current conditions,
RASP Region: | Blanchard | Fraser Valley | Tiger | PNW big pict.
Smart phone access to many weather resources | Windgrams for smartphones | Blipspots | Ft. Ebey Page | Horizontal atmoshpheric slices loop over time. Mechanical lift (and sink) from topography and convergence. | Blanchard Current Conditions -- sock, ceiling, winds